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How do small unmanned fixed wing aircraft protect themselves against lightning strikes?
I'm asking this question after doing a small research project to see if a small UAS can fly through thunderstorm and trigger lightning strikes. I've googled a bit, and all I've seen are large aircraft getting hardened against strikes.
From what I've read and looked at, all the aircraft use metallic mesh or metal skin to dissipate the heat and voltage. I'm thinking something similar could be done for for a UAS, but don't know how to analyze the system to make sure it can handle the strike.
How does one go about analyzing a structure to see if it can handle lightning strikes? Has anyone flown a fixed wing UAS through a thunderstorm to trigger lightning strikes?

This is a duplicate question for numerous answers on "Static Wicks".

You design your structure, as in larger aircraft, considering where the strike could potentially hit first, and where it would leave.
The rest is electrically bonding everything together, and creating a continuous electrical route from each entry point throughout the structure to the potential exit zones.
Calculating or measuring the electrical resistance throughout the paths is the way to quantify the effectiveness of the design. If it’s zero, the lightning would not hit this aircraft (or would pass through it without causing any harm). However, this conflicts with the scenario of triggering lightning strikes.
To attract lightning, you can simply put a sharp, massive metallic pole, in electrically isolated from the rest of the fuselage.


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Can an ultrasonic sensor mounted on a drone pick up another drone strongly enough to sense and avoid?
I am asking this question to see if mid-air collisions of drones can be prevented using simple analog sensors. Can an ultrasonic sensor mounted on a drone pick up another drone strongly enough to sense and avoid it?
I know that the sensor is range limited so the aircraft cannot be flying towards each other very fast, but to even do any sense and avoiding, can this sensor work? Or does the drone not provide enough of a return?
Also, could the range of sensor be increased if both drones emitted ultrasonic energy to be picked up on the sensor more strongly at a distance?

by "ultrasonic sensor" do you mean an ultrasonic proximity sensor, or an ultrasonic microphone?

Isn't the range of high frequencies much lower than that of low frequencies?

Bats should be proof enough that it works, right? So why ask here?

I think its going to have a very hard time hearing it through the sound of it's own blades hitting the air.  That plus the vortexes created by the movement of the air would make sound detection very very tricky at best.

@PeterKämpf Bats aren't beating the air with their wings 1000 times per second.  Plus, a bats ears and mouth are ahead of the wings, so they have clean air to hear through.  This is more equivalent to a hummingbird trying to use sonar when its ears are placed between its wings.

@JayCarr, propeller/rotor noise is still not ultra-sonic, so it can be filtered out just fine and there is nothing saying the sensor is mounted in the middle—it can still be mounted ahead of the wings or rotor on the drone.

The range of the ultrasonic sensors ends up at somewhere 5 meters (here is the pre-configured search). However a simple sensor would only measure the distance, by the signal travel time. It does not provide the angular co-ordinates or exact location. Same problem as with the simple radar.
May make more sense to fit the drones with transponders so that they could actively broadcast they own location, speed, orientation and intentions to other members of the flock.

So he would need two sensors to pick up the angle then.

Three at least, to get azimuth and elevation. Plus some brains to calculate relative velocity and decide what to do about it. That is: a little more than just sensors.

This question doesn't really address the issue of noise distrubances caused by the operation of the drone carrying the sensor...  The microphone may be able to pick up the sound under normal operations, but at 50kph in flight?  I dunno...  You at least need to address it.

There's a video of a ultrasonic-collision-avoiding drone. So, in principle, this should work. Also, note the reflector surface used by the guy in the second half of the video - it's not incredibly big (but, indeed, approximately orthogonal to the propagation direction of the finder beam). So, let's count this as "it could work, in principle" - especially, if you put more power into the outgoing sound waves, to pick up the weaker return signal of a drone.
But, as consumer drones already reach speeds up to 72km/h, it looks a bit unlikely that this is will become the go-to technology for avoiding a possible head-on collision. In this scenario, two drones will move in on each other at 2x72km/h, which is 40m/s. By using the numbers of @h22's answer, we get 1/8th of a second between earliest detection and impact. In this time you need to come up with a solution, and you need enough thrust to divert your course far enough to avoid the oncoming traffic.
I'd expect the physical reaction time of the drone - the time until max. diversion thrust is applied - as well as the amount of thrust, to be the limiting factors.
And your generic solution ("it's an obstacle, just fly upwards to avoid") may not work, as your counterpart may have the same idea, resulting in the same collision just a meter higher from ground.

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What are the limitations of the aerodynamics modelling used in flight simulators?
I've asked around, and it seems all flight training programs use a combination of flight simulators and aircraft flights to train pilots. This works well for most pilots who fly airliners which don't spend much time in turbulent air or close to obstacles, and the flight simulator aerodynamics are very close to what is experienced in actual flight.
My question is where do the flight simulator aerodynamics models breakdown? I was wondering this in relation to rough air flying skills, where the aircraft or helicopter flow field interacts with surrounding environment (like inside a convective storm or near obstacles like trees and buildings) I would imagine these are situations that are hard to model since it depends on accurately modelling the interactions, which are difficult to run quickly enough for running a flight simulator. Fixing this by only doing flight training seems dangerous, especially for newbie pilots since the margin for error is very slim.
Personally, even though its more expensive than a flight simulator, a first person view drone would be a good intermediate step between the flight simulator and full scale training, with the response characteristics and control interface being the same as the full scale aircraft or helicopter.
That said, I don't know where the flight simulator aerodynamics begin to diverge from what is actually is experienced in real life, so the drone might be completely unnecessary. I'd love to see how this problem is resolved now.

That training drone would need to be full scale to have the same flight characteristics. So it would end up as the actual aircraft minus pilot plus a lot of equipment to make it remotely controllable and return comprehensive signals about attitude and motion. Which should all be fed back to what would essentially be a simulator. That said, where should it fly to not be a hazard for people on the ground?

@RobVermeulen -- well, the Edwards range is a good place to start if you want to do funky test flying without worrying about hurting things on the ground....

You're right @UnrecognizedFallingObject. Didn't think that big, living in The Netherlands where anything taking off will soon appear over somebody's roof. Even if that roof is below sea level.

Size matters here. Big aircraft have more inertia and take much longer to respond, but can equal out small-scale turbulence better. Your drone idea for training will not be representative of the big airplane at all.
Turbulence can be modeled quite faithfully - you just need to fly once through rough air, collect all the data and replay it in the simulator. The changes due to different pilot responses can be added on top without much loss in accuracy against a real flight.
Where models for airliner crew training break down is when the linear range of aerodynamics is left. Their post-stall and spin behavior is most likely not suitable for training, but that is not what they are designed for. Military aircraft simulators can even model the post-stall regime well, but need a lot of aerodynamic data, and most of that data is from wind tunnel models and not from real flight test.
What the simulation does is to plug the actual values of angle of attack, angle of sideslip, airspeed, power level angle and control deflections into matrices of coefficients and calculate the result from linear addition. That works well as long as the forces vary linearly of the flow angles, and correction factors will give you still good agreement with reality well into a stall. The coefficients are a mixture of CFD, wind tunnel data and flight test data. Gust loads can be modeled with Markov matrices which produce a realistic distribution of gust intensities, so even external, stochastic factors can be modeled faithfully.
I have less knowledge of helicopter simulators, and I would assume that flying near tall buildings can only be modeled in general terms, but not well enough to train a pilot for a specific location and weather condition.

There are two aspects to simulation error: the aerodynamic model error and less commonly known, integration algorithm numerical error.
Aerodynamic models tend to break down in the transonic and post stall regime of flight for two reasons: lack of data due to safety or cost, and poor predictability created by non-linear response in turbulent flow/shockwave formation. That is, the risk to reward would prohibit the conduct of full post stall(spin) test program on a wide body airliner. There is no justifiable reason to do so in relation to the aircraft's role or certification requirements. Contrast this to a fighter jet that might require this.
Buffet, ground effect, external turbulence, and wake turbulence can all be simulated with reasonable accuracy according to the requirements and complexity of the sim, which is dictated by the aircraft role. Note that buffet can occur prestall. Despite the difficulties in predicting post stall handling qualities using tools such a CFD analysis, it is possible to collect reasonable data in relation to handling characteristics with detailed and thorough flight test.
Simulators are usually hamstrung by model complexity and realtime computing power.  For that reason,  integration algorithms are chosen to best suit the simulation application. Airliner sims tend to use forward predictive algorithms such as Adams-Bashforth-Moulton predictors, as the flight envelope is limited to regions where strong linearity exists. Conversely  this algorithm would induce significant errors even if reasonable aerodynamic data existed in post stall, spinning flight. Other algorithms do exist and are better suited for this application. Brute force may also be an option.
Using a drone could be beneficial, however it would be difficult to accurately mimic moments of inertia characteristics, and post stall handling due to Reynolds effects. Ok for generic simulation, but not ok when replicating larger scaled aircraft.

Would it still be a problem using euler integrators while running the simulation @ 3000 Hz? That rate seems to be no problem for an average laptop.

Simple Euler integration numerical methods can be a solution, but the problem depends of the complexity/resolution of calculations, which can only be done in serial, not parallel. My experience with an average lap top is that it can bog down quite quickly such that the errors increase significantly.

Full motion simulators have no problems reproducing turbulent flight effects: they don't need to compute turbulence in real time like in CFD, they just replay one of several pre-recorded wind gust variants, and the reaction of the simulator flight model on this pre-recording is just a matter of mechanical physics modelling.
That is - as long as variables such as angle of attack stay within normal flying bounds, and do not enter fully established stall territory. That needs to be modelled in a different way, indeed like Peter says from wind tunnel data, combined (unfortunately) with data from flight recorders of crashed aircraft. This links to a site describing full stall simulation addition, certified by FAA. (I've long hesitated to link to it due to it being a commercial product and I've done business with the manufacturer).
Some confusion is created by Xplane using real-time laminar CFD. Turbulent real-time CFD has all kinds of challenges, amongst others the stability of the real-time loop like @busdrivingtupperware mentions. Flight training simulators don't use real-time CFD for computing flight dynamics, because computers are not yet powerful enough. Only a matter of time: code that used to run at 30 Hz on a super duper computer 25 years ago, now runs at 3000 Hz on a laptop. And model stability is usually not a problem at high iteration rates.

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How can one quickly estimate interference drag for a configuration?
I'm doing some work on streamlining my process for designing new aircraft, and in the process creating/looking for rules of thumb and shortcuts one can use when designing. I'm currently in the process of creating a way of quickly estimating L/D of an aircraft in conceptual design stage. I'm looking for something that doesn't involve a ton of CFD or windtunnel time, and can be incorporated into a spreadsheet. It needs to be +/- 10% of the actual L/D achieved.
I've been able to figure out lift and drag of individual components pretty easily. However, I'm having trouble with figuring a quick way of estimating interference drag. What shortcuts do experienced designers use for estimating interference drag quickly?

Use Sighard Hoerner's Fluid Dynamic Drag. It lists tons of wind tunnel and flight test data for a wide variety of configurations and flight regimes.
Interference drag has several sources:

Flow separation due to the coincidence of the pressure rises of two bodies. Each of them by itself would show attached flow, but in the vicinity of a similar body with its own pressure rise, the flow separates. This is most pronounced at low speed.
Addition of the accelerated flow of two bodies in transsonic flight. While each of the single bodies has no supersonic pocket around it, both in combination will cause a local supersonic area with a subsequent shock.
Disturbance in the spanwise lift distribution, such as wings interrupted by the fuselage or engine nacelles.

Look for areas where one of these conditions is fulfilled, and then try to find a similar case in Horner's book to estimate its severity. Note that all interference drag varies with speed and angle of attack. Doing so carefully will bring you within 10% of the real drag, but needs some experience.
In the end, drag estimation is like bookkeeping. You need to carefully add each component and make sure to avoid double-counting or mixing up reference areas. Sorry, but if you want a good result there are no shortcuts.


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What is the typical reaction time for most pilots?
I'm doing a manned aircraft design and make it easy to fly by making it hard to enter a pilot induced oscillation (PIO). I got a range of natural oscillation frequencies for my design in pitch, roll, and yaw, and now I'm trying to see if the period of these frequencies fall close or far away from most people's reaction time. I searched on Google, but only got data on twitch time, which doesn't seem applicable for an aircraft where some muscle power will be needed, hence my asking this question.
My reasoning is that if it falls an order of magnitude below or above the reaction time of most pilots, the aircraft will be easy to fly (as long as it doesn't go through extreme high G maneuvers). An additional question I have related to this is, how can one design an aircraft to make it difficult for pilots to enter PIO's?

Are you looking for commercial pilots? military pilots? General aviation guys? or everyone? The subset of people will greatly change the answer.

The average person who is not trained as a pilot. So I suppose general aviation.

There is no need, nor reason, for a pilot to have better reactions than anyone else. So just use typical figures.  Stories about super human reflexes are nonsense since a reflex is a chemical response to a stimulus which has a fixed maximum speed.  It might get worse, but it can never beat the maximum.

You make it sound as if you only looked at rigid body modes. This is not enough, add elastic modes and the delay of the control system on a pilot's reaction. And keep in mind that avoiding frequency neighborhood is a necessary, but by no means sufficient step to make an airplane easy to fly.

Would be great to know what type of an aircraft your design is. Also Fly by wire or fly by cable, etc. PIO avoidance is quite an art rather than a solved (trivial) problem.

Its a bit dated but here is a paper published by the Navy on visual reaction time you can find. Keep in mind these are navy pilots, often considered the best of the best and in peek physical condition. Based on the publish year I would suspect all subjects were male as well.
Here is another study by NATO on reaction times for pilots on low sleep.
This is a nice study comparing the reaction times of pilots to non pilots, might be of some help.

An additional question I have related to this is, how can one design
  an aircraft to make it difficult for pilots to enter PIO's?

This is an interesting question and in some regards could be its own question here. One of the big debates (mainly between Boeing and Airbus) is if systems like this should exist and who has the final say in terms of control deflection. Airbus takes the approach that the computers should prevent the pilot of say pulling back on the stick and stalling the plane. While Boeing generally allows pilots to be the final say and while their systems will warn of a stall you can ultimately pill back the column until the plane stalls.
In terms of how you would design something like this you would have to limit control input after an approach to oscillation was detected.

Unfortunately, even Airbus airplanes don't always stop you pulling the stick back and stalling the airplane. :-(


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Which commercial aircraft can stay in the air the longest?
Which commercial aircraft, when fully loaded with fuel (and passengers and luggage up to its max takeoff weight), could stay in the air the longest without landing, and how long could it stay in the air? What conditions would it need to have maximum possible endurance if the plane had no intended destination to land or particular flight path? (This is for a fictional story.)
Note: I was thinking commercial jetliners when I wrote that, and I still am, but I was accidentally unclear about it. That's preferably what I'm looking for, though.

You just wait until the start making commercial Solar Impulses.

A bit of a side note: These guys are a civilian commercial outfit that does refueling (on contract to the military mostly) but still counts as a commercial aircraft. Im not sure if the refueling tank is connected to the main system but if it is I assume it can stay aloft for some time more than a regular aircraft.

The Goodyear blimp?

Is a space shuttle considered an aircraft?

@user3528438 - When it's in the atmosphere, yes.  Though it's hard to make the case for it being a commercial aircraft.  I don't think anyone has ever paid to put something on a space shuttle because of its atmospheric capabilities.

Having recently read some novels in which the aircraft operations descriptions were rather sketchy (I'm looking at you, Clive Cussler), I appreciate that you're attempting to get some reality into your story!

A commercial airship, like the 'Zeppelin NT' can stay airborne for 24 hours.
The record (for a military US-Navy blimp in the 1950s) is 264 hours, 12 min. It covered more than 13,000 km.

Record flight of 8,216 miles in 264 hours. Lakehurst NJ to west Africa to Key West FL non-stop. (Source)


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My windsock is erect, what does this mean?
I know that airport windsocks are calibrated to reach full erection at a particular wind velocity. At half that speed, the first half of the windsock should be erect and the second half should droop sorrowfully. At one third the speed it will be one third, and so on.
Trouble is that not all windsocks are calibrated the same way. How do I find out what wind velocity will bring my airport windsock to a fully erect state?

It means a smokin' hot wind just blew by.

. . . It means your windsock is very happy. The local pilots maybe not so much.

Now I understand the origin of the phrase "A stiff breeze".

If it lasts longer than 4 hours, consult a meteorologist.

Windsocks come in various sizes and speeds, but an FAA Standard Wind Sock aligns with the wind at 3 knots, and is fully extended at 15 knots like CGCampbell pointed out.
A typical wind sock (at least around here) looks something like this:

The stripes are actually useful:

The first stripe indicates a 3-knot breeze
(The wind sock has turned and aligned with the wind - usually you should look for an anemometer near the wind sock to determine if there's any appreciable wind because often the first segment is held open by the frame.)
The second stripe is ~ 6 knots
The third stripe is ~ 9 knots
The fourth stripe is ~ 12 knots
The last stripe is 15 knots or higher
If the windsock is missing you probably shouldn't be at the airport.
If the pole is missing you're probably on your way to Oz.

(You can actually get a far more precise estimation if you're willing to do some trigonometry, but this works well enough for most purposes.)

@AlexanderGruber Nothing hard - this works better with a "floppy" wind sock that doesn't have its throat held open (or something like a wind streamer / flag), but basically sin(windsock_angle) * full_extension_speed should give you the current wind speed (the angle is from the pole, so hanging limp is 0 degrees, and sticking straight out is 90 degrees). See also "Wyoming Windsock" :-)

@voretaq7 "First officer, bring us in close, and fetch me my protractor!"

@voretaq7: Just a heads-up, but the "Wyoming Windsock" link is broken.

According to the FAA, Advisory Circular 150/5345-27E, dtd 26 Sep 2013, Paragraph 3.2.2,

3.2.2 Dimensions
The taper or the fabric windsock from the throat to the trailing end must be designed to cause the
windsock to fully extend when exposed to a wind of 15 knots (28 km/hr or 17 mph).

The paragraph, 4.2.6 Windsock Extension gives the variance of wind speed allowed which should still cause a full extension of the wind sock, but that paragraph appears to need editing to put in the starting values for mph and km/hr, 17 and 28 respectively, which are indicated above.

4.2.6 Windsock Extension.
Test the windsock to assure that it extends fully when subjected to a wind of 15 (+2,-1) knots (+3.7,-1.8) km/hr or (+2.3,-1.2 mph) ).

So, for instance, the sock should be fully extended from 15.8 mph through 19.3 mph.

I also read a comment in a blog that indicates that the EASA was coming out with (new) regulations about windsocks, but am having difficulty finding anything at the current time.

Yeah I wasn't able to find anything about an EASA Standard Windsock. Canadian windsocks are the same 15-knot standard as the FAA uses though. (That site also gives the alternate, and maybe easier, explanation of "5ks for every orange stripe sticking out", but I always like the 3kts-per-segment one I gave in my answer because it's a little more precise)

I'd feel a lot more confident about that FAA Circular you cite if it didn't seem to be missing the actual threshold values in km/h and mph. Presumably, it should say something like "15 (+2,-1) knots (27.8 (+3.7,-1.8) km/hr or 17.3 (+2.3,-1.2) mph)."

@IlmariKaronen I edited my answer to fill in the blanks you noticed. Thanks for that.

The main function of the  windsock is to show from which direction the wind blows. The faster the wind blows, the straighter and more horizontally the wind extends.
As per FAA standards a 15-knot (28 km/h; 17 mph) wind will fully extend the properly functioning windsock. A 3-knot (5.6 km/h; 3.5 mph) breeze will cause the properly functioning windsock to orient itself according to the wind.  If the windsock has blown away, the wind is greater than the 75 knot design limit.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5345_27e.pdf
Windsocks are accurate only within a small radius. In those airports where there is  only one windsock and it's alongside the midpoint of the runway, the only thing of which you can be certain , is that, the wind at either end of the runway  will NOT  necessarily match. This explains  why  many airports have windsocks at both ends of the runway. The sock in the middle tells traffic which runway to use, but the windsock at the end of the runway tells the pilot what to expect on approach.
Note that the correspondence between wind speed and degree of extension and straightening will varies from one model to another. You can calibrate the  windsock with the help of a  anemometer.
After installing the windsock on the ground , use the anemometer to calibrate the shape and orientation of the windsock to specific wind speeds. The anemometer (wind meter) should be held at  the same height as the windsock’s larger opening . Point it into the wind and  record the  wind speed reading.

Myth alert! There is a somewhat widespread belief in the most accepted answer here. It is not true that there is a 3kt relationship per segment of the windsock. Those who claim so provide diagrams of this but never photographs. Also the FAA does not specify this in their specification for windsocks. Windsocks are designed to fly straight, it is the angle of the dangle which indicates windspeed. The first segment (the one nearest the mast) is often rigid so as to keep the rest of the windsock from entangling itself around the mast. But other than that first rigid section you will not see a bent windsock. FAA spec: http://www.faa.gov/documentLibrary/media/advisory_circular/150-5345-27D/150_5345_27d.pdf

Welcome to Aviation.SE! You have to pardon my partial skepticism, but where in the document you link is there indicated that the "3 kt rule" is a myth? it is neither refuted nor mentioned, and it could have been behind the design of the sock size (length, diameter, fabric selection, etc.). Moreover, the first segment being rigidly connected is already addressed in the accepted answer

in addition, the document you link has been superseded by the newer edition linked in D_S' answer

Actually there is more than one patent for windsocks (actually, there are several). One design operates as you indicate; the whole thing beyond the stiffener section droops at an angle corresponding to wind speed. Another patent is designed to operate as Voretaq mentions, with wind speed indicated by which section is drooping.

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Are aircraft being fitted with brighter anti-collision lights?
I live and work near to DFW airport. Yesterday, I noticed an inbound jet with obviously brighter strobes (anti-collision lights) than any other jet I've seen before. (I believe this was an American Airlines Jet with an engine under each wing.) Does anyone know if aircraft are being fitted with brighter anti-collision lights? This particular aircraft was really noticeable against the low overcast clouds.

Newer aircraft use LED lights. Don't know if these are brighter than the old-school bulb ones,

Probably was a 787... I noticed that the time their red anti collision light is on (per flash) is quite long, so it appears to be very bright.

For those voting to close, lux is the unit we use to measure brightness. There is nothing opinion based about whether or not newer anti collision lights are generally brighter than old ones.

@expeditedescent: +1. But with light, there are multiple traps: Lux is used to express the brightness of a surface (lux=lumen/m²). Source flux is expressed in lumen for the total flux or candela for a flux in a given angle (intensity).  The proper unit to express perceived luminosity would be cd/m². I can't remind the whole story without looking at a reference though.

Its possible they are just fresh halogen bulbs and brighter than others you have seen but your key line is:

against the low overcast clouds

Low clouds, fog, and the like give strobes something to reflect off of so they seem brighter in a localized way. I cant find a great image of it but this video showing the graphics updates in X-Plane 11 show the phenomenon
fairly well. On a cloudless night the strobes (an most aircraft lights) have little to reflect off of so they seem darker when looking at them. If you watch departures and arrivals in similar conditions you will also see the landing light throw a similarly "visible" beam. This is all somewhat similar to how laser light is visible in fog.

LED aircraft lights can be (and usually are) made much brighter than incandescents due to the former's much lower power draw, so that may be what you're seeing. However, strobes are a bit more complicated than steady lights.
According to this analysis, the time-intensity product is 80cd-s for flashtubes and 200cd-s for LEDs. While the latter seems like 2.5x the light, the author notes several perceptual phenomena that may mean they're less noticeable in practice.

Small planes too.  I plan to put brighter lights on my plane soon.
LED to replace the wingtip position (red/green) and strobe lights, and white on the tail.
https://www.aircraftspruce.com/catalog/elpages/microburstIIIwhelen.php?gclid=EAIaIQobChMIxrLc876J4AIVibjACh0mCgigEAQYBCABEgJG_fD_BwE
LED landing light too
https://www.aircraftspruce.com/catalog/elpages/whelenparplus36.php
Should be brighter, and use less current.
See and be seen!

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Why is white light more visible than red and green on this Cessna model on a sunny day?

Source: https://i.ytimg.com/vi/hNgu1vypV3g/hqdefault.jpg
VS

Why is the white Landing light more visible on a fine sunny day and not the other two? I would have assumed the Red one to be most visible during flight, followed by Green but from a distance on a sunny day you can only see the white Landing LED very clearly but neither of the other two. Could it simply be because of the intensity of white light being more (having 2 bulbs) as compared to the other two having 1 bulb each?
This picture does illustrate the position of lights but since it was taken in a dark setting it doesn't do justice to how it appears during the day. Those red and green lights are not visible at all from any distance beyond a few meters.
When its a little dark (evening / cloudy) they are clearly visible.
Please Note: It is not really so that I expect to see all these 3 lights clearly on a bright day, obviously against sun light they stand no chance. I am just curious as to why the colored ones are far less visible than the white one.

sort of related: You dont use nav lights that often during daylight.

Was this pictures really taken in broad daylight? It looks more like dawn or dusk to me. Plus: It's a model. The representation of real aircraft lighting is not given, as the lights are only scaled in size. On a real Cessna, they wouldnt be so visible in daylight, not even the landing light.

Yes this picture is not a daylight one, I chose it just to present the lights themselves

Was the traffic coming at you, aka opposing traffic?

Correct, i was flying it myself and i was observing the lights on landing and also on low passes

Same situation as with your car headlights high beams being much more visible than indicators, even though indicators are meant to be a visible signal, not high beams.

Navigation or Position Lights are meant to be used at night-time and can be used when precipitation or weather in general deteriorates to the point where the lights will help you identify an aircraft's position, distance and orientation of the aircraft. During daylight operation, the use of navigation lights is not required as you can identify the shape of an aircraft against the horizon or background.
Navigation lights are also installed at the sides of the aircraft, spanning a range of 110° measured from the extended centerline of the aircraft to each side.
The landing light however is pointed directly along that extended centerline, which makes it easier to spot if the aircraft is approaching you. It also is of higher intensity than the navigation lights, as it needs to give a pointed illumination for a larger area in front of the aircraft, rather than giving a steady and 110° wide illumination.

(Image Source: Wikipedia - Author: Trex2001 Clem Tillier)

The navigation lights are meant to give away the airplane's orientation (i.e. which direction it is travelling) at night. The red and green lights are small. Their purpose is to be observable from a long distance, which only requires a small light. For the same reason, the anti-collision red lights of tall structures are small as well.
The landing lights (white light) are meant to illuminate the runway, taxiway or any terrain in front of the aircraft. The light must travel to a certain distance in front of the aircraft then bounce back. They are very bright. To experience that, go to a busy airport at night and stand near the approach end of a runway. In fact, standing next to an airliner with its landing lights fully on would likely damage your eyes.
Landing lights must also be turned on when any aircraft enters an active runway. Here they serve the same purpose of turning on the headlights of your car at night: to make sure others can see you. This regulation came after an airliner landed on an occupied runway at night. It was determined that the plane on the ground blended in with the runway lights, and the pilots of the landing aircraft were unable to spot it. Had the plane turned on its landing lights, the very bright light source would have give away their position and alerted the crew to abort its landing.
The model is simply a replica of the real life scenario.

Their purpose is to be observable from a long distance, which only requires a small light; But that's exactly what they aren't doing

And knowing the orientation of an aircraft is an extremely important factor in model aviation as well. Not that without the lights its impossible to tell but was just curious and disappointed that they didn't do their job well but i guess on a model they are mostly for cosmetic reasons because night time model flight is a challenge in itself with or without those. +1

@HankyPanky During the day you don't need the lights because you can see the aircraft.

Downvote for misinformation about supposed landing light use requirements. There is a difference between an operable equipment requirement and use recommendations. Company SOP is another variable.

The OP asks why the white "landing light" is more readily visible during the day than the red or green nav lights.
The primary reason for the white light being more recognizable in this instance is that it is providing more photons than the green or red lights. The landing or taxi lights consume more power and produce more light than the nav lights.
In general, the eye sensitivity is a function of the photons received, adjusted for the sensitivity of the eye for the color(s) received, and adjusted for contrast (brightness gradient). The peak photoresponsivity of the human eye is about 560 nm, which is a green-blue color and shifts to 507 nm at night, which is more blue.  The white light of the landing light is comprised of most or all colors which the eye is sensitive to, normally considered colors with wavelengths ranging from 400nm (violet) to 700nm (red), where nm is the wavelength of the light, nanometers, not nautical miles.
But to be clear, the visibility is a function of amount of radiation emitted, adjusted for the sensitivity of the eye, and in the OP case, the answer is simply that the landing lights have a much higher level of emissions than the nav lights.
As a tangentially relevant aside, the human eye, when night accommodated, has a very high quantum efficiency.  Quantum efficiency is the ability to convert a photon (the smallest unit or packet of light) into a neural response which is recognized by the brain. Once impressed by the ability to observe lit cigarettes from 5000 ft and higher altitudes while doing surveillance work, I later investigated the responsiveness of the human eye. In general, a younger eye can reliably detect single photons. Things like available nutrients affect that, those nutrients including oxygen. Lay on the ground on a moonless night, and look at the stars, and then take a breath or two of oxygen, and suddenly there will be many more stars.
To summarize, the reason the white light cited by the OP is more visible is that it is giving off more photons which are detectable to the observer.

Great answer. This is more of what i was originally looking for


text:
I don't quite understand the bypass air
I am writing an essay on how a jet engine works, so I need specific answers on this.
What percent of the air that is sucked into the engine is bypass air? I have heard that bypass air provides about 60% of the thrust.  How does cold air provide thrust?  I was under the impression that hot air makes much more thrust than cold.

"How does cold air provide thrust", the big fan at the front of a turbofan is mostly a propeller, the rest of the engine is here to spin the fan.

Cold air accelerated backwards provides forward thrust by reaction. What really matters is the amount of mass accelerated backwards. Its temperature is not important...
Concerning the 'percent of air sucked', it depends on the design. A pure turbojet doesn't produce 'bypass air', and a turbofan may reach a ratio of 10:1, that ratio being the relation between the mass of 'cold' air pushed backwards by the fan in a given time and the mass of air that passes through the combustion chamber...

It all depends on the bypass ratio of a turbofan engine, with is the ratio of the air flowing through the fan and cold section diffuser vs the airflow through the gas core of the engine.  High bypass ratios can have at or greater than 90% of the total airflow moving through the cold diffuser of the nacell with only 10% or less of the air moving through the gas core.  The bypass air also produces nearly 90% of the reactive thrust from the engine as well.  This is reversed in low bypass or turbojet engines where very little or no reactive force is created from bypass air through the engine core.
What produces thrust is a change in momentum of a mass of air over time.  This can be accomplished by the fan and cold diffuser, in fact a turbofan engine is just that - a ducted fan powered by a gas turbine engine, functioning much like a turboprop.  The major advantage - and the reason we use high bypass turbofan engines to power commercial airliners - is the fuel savings in the design for lower speeds.  Engineers found that the more air which was fed through the gas core, the more fuel would need to be burned, which decreased efficiency of the engine.  For lower speed flight the change in momentum of the air through the engine could be lower and save fuel by simply accelerating the air through a fan or first stages of the LPC, then bypass it around the core through a diffuser and out the back of the engine.  The design provides acceptable amounts of thrust in the Mach 0.85 - 0.90 range.
Supersonic flight requires a higher change in momentum for the required impulse and this is only achievable by means of higher gas enthalpies prior to exiting the diffuser, making the turbojet the most realistic option for cruise in the Mach 1 - Mach 4 range.  Ramjets as well work good in this flight regime but are not capable of effective operation in low speed flight, requiring additional power plants for operation here.


text:
What is the lump under the English Electric Lightning's fuselage?
What is the lump underneath the English Electric Lightning's fuselage?

Source: www.forwallpaper.com

Questions on SE normally expect a bit of research ahead of time.  This was obviously not done in this case.  If you mouse over the down vote button, you will read the following text:  "this question does not show any research effort."  It took me less than 45 seconds to find the obvious answer.

@KorvinStarmast I understand your point, but so far the consensus on this site is that we answer questions, we don't tell people to RTFM or JFGI. Just because you can find an answer quickly doesn't mean someone else can, or that the answer is exactly what they're looking for anyway.

@KorvinStarmast This site is generally speaking supposed to be beginner friendly, I'm actually pretty surprised by all the downvotes.  I'm with Pondlife though, just because it's easy for one person to google doesn't mean it will be for another.  I've struggled on google searches that should have been obvious before and just settled on asking a question...  It happens, even to the best of us.  There's no reason we can't just answer the question here.

@JayCarr OK, I'll drop the grumpy old man act.  DV rescinded.

Stack Exchange is different to any other site. I encourage you to have a look around the help centre.  Learning how to ask good questions is part of learning how to learn - if that makes sense! I've also opened a meta-discussion question on this topic which you might want to follow.  I hope that this site becomes a great source of information with you but, I would leave you with the thought that the quality of what you get out is determined by the quality you put in.

@KorvinStarmast Thanks much good sir!  I know you have some long experience, us n00bs can probably get pretty annoying at times.  I appreciate your patience :)

Hey, anonymous, some of your questions may actually work a bit better in chat, perhaps you would like to join us there?  http://chat.stackexchange.com/rooms/12036/the-hangar


text:
Is there a detection method available to detect a plane without using RADAR?
If we don't have RADAR, is there any other method to detect flying objects?
All flying objects disturb the air around them. Is there any method by which we can detect that this air turbulence is from an artificial flying object or a bird etc.?

What about eyeball Mk. I? Works fine most days. On a more serious note, a wide range of the electromagnetic spectrum is suitable for object detection at a range, like infrared. Radar is just a part of it.

Your question has ambiguities: 1/ What is radar? If this is radio detection and ranging, then lidar qualifies. 2/ Detection from ground, airborne or from orbit? From orbit satellites use telescopes (visual). Airborne there are alleged technologies that defeat stealth aircraft. Also this. 3/ Performance? Sound detection but low sensitivity.

Sure, there are ways of 'seeing' the disturbance of the air around an aircraft. But the problem with this would be that there would be so much erroneous noise from other things like: wind, cars, trees, etc. basically anything that could disrupt the laminar flow of the air would cause disturbances.

One of the things people used before radar was sound. These days the technique is called Acoustic Radar but of course it was not called that before radar was invented because the word "radar" did not exist. Do a google image search for "acoustic aircraft detectors" : https://www.google.com.my/search?q=acoustic+aircraft+detectors&source=lnms&tbm=isch&sa=X

@slebetman: "Acoustic Radar" seems quite strange as radar means radio detection and ranging. Acoustic waves have nothing to do with radio... they are pressure waves.

@mins: Yes people are strange and misuse words all the time.

Radar is, by far the most widely known and used of the active detection methods.
Passive methods include the use of visual and infrared search and track systems such as the F-14's Television Camera System or the Eurofighter Typhoon's PIRATE infra red search and track systems.

there's also the secondary radar systems, which aren't exactly radar, if you are thinking of radar in the sense that an electromagnetic pulse is sent from a transmitter and is bounced off of the skin of the aircraft and returns to the receiver at the radar site.
secondary systems are used to correlate the primary radar data with info from the air-crafts' transponders. the system sends out a radio transmission of various pulses which interrogates the transponder of any aircraft that receives it. The transponder then sends out a series of radio pulses on a different freq which the system RXs.


text:
Why doesn't the plane accelerate/move forward when it's at rest, if the propeller is spinning?
I'm having difficulty seeing the difference between a stationary plane and a moving one.

When you start the engine in the C172, the blades on the prop are spinning - but the plane doesn't move at all.
When taxiing out, it feels like the forward motion is being provided by the wheels - like in a car.
When taking off, you can audibly hear the change with the throttle increases.
In cruise, the plane almost looks the same from the inside as when it's on the ground (i.e. prop spinning). Which is where the weird psychological block is for me - the plane feels stationary even though the horizon/backdrop is moving towards you, and i get that fear kick in that it could drop because there's not enough momentum.

I'm trying to understand what the propeller is doing in each of these stages: rest, taxi, take-off, and cruise - as well as how the plane is pushed forward with thrust, if it can just sit there and not move with the prop spinning away.
My question(s): what's happening with the engine, throttle, and propeller that provides the thrust, and/or forward momentum? Does the plane stay stationary when you turn the engine on because there isn't enough RPM to draw it forward, or will it automatically pull forward and the brakes are just being held on? Does the plane accelerate in proportion to the prop RPM? What's different with the prop when stationary, compared to when it's taxiing or taking off?

Hi, and welcome to Aviation.SE.  It's good that you came here and asked these questions but, it is not the best thing you could have done.  Questions like these should first of all be discussed with your instructor. It is vital in order to become a competent, safe pilot, that you build a two way relationship of trust with your instructor.  If they cannot, or will not not answer questions like these, then you should find another instructor. Over the next 60 odd hours of flying together, you will both put your life in the others hands. That demands trust.

"the plane feels stationary even though the horizon/backdrop is moving towards you, and i get that fear kick in that it could drop because there's not enough momentum."  This is why you scan the airspeed indicator and practice stall recognition.  I see that this is a year and a half old, hope your training is going well!  :)

When you start the engine in the c172, the blades on the prop are
  spinning - but the plane doesn't move at all.

When the propellor is idling its obviously moving air, this you can see, feel, and hear, however its simply not spinning fast enough to provide enough thrust to overcome the force of the plane sitting on the ground. Basically this is comprised of friction air resistance as well as some limited brake pressure that is usually applied. With fresh bearings, on level ground an idling prop may very well pull a plane forward. For the record it is a matter of certification that the brakes on an aircraft can hold it in place at full throttle. It also takes a bit more force to get a plane rolling than it does to keep it rolling. You need to break static friction to get rolling but then only provide enough power to overcome kinetic friction.
Generally speaking static friction is higher than kinetic friction,

(source)

When taxiing out, it feels like the forward motion is being provided
  by the wheels - like in a car.

The first time you are in small plane you associate it with a car. You
equate that feeling with a car and thus you think intuitively that the tires are pushing you. In a car you could not be able to tell the difference between a front wheel drive and real wheel drive setup the idea is the same here.

When taking off, you can audibly hear the change with the throttle
  increases.

I don't think there is a question here.

In cruise, the plane almost looks the same from the inside
  as when it's on the ground (i.e. prop spinning). Which is where the
  weird psychological block is for me - the plane feels stationary even
  though the horizon/backdrop is moving towards you, and i get that fear
  kick in that it could drop because there's not enough momentum.

The plane feels stationary because you are in unaccelerated straight and level flight. In other words the forces are balanced about the aircraft. You feel nothing because there is nothing to feel ("feeling" is really another word for acceleration). This is different than a car, our road system lends its self to speeding up/slowing down often and unless you are on a very straight highway at night when its empty its less likely you are in unaccelerated movement in a car. The twits and turns of the road and the constant passing and slowing down of cars leads to a "feeling" of movement.

I know I hold the brakes when starting a C172, I was surprised when I hunted down a POH that didn't mention brakes during start :).

@bartonjs Im not sure what 172 you were flying but in this POH the BEFORE ENGINE START section clearly states,  "4. Brakes -- TEST and SET. "

d'oh. I jumped right to ENGINE START (With Battery), then saw you'd answered and stopped looking.

"In a car you could not be able to tell the difference between a front wheel drive and real wheel drive setup" - you certainly can. I'll tell you as soon as you start to move which end is driving the car.

In the air you have no close-by reference to judge your speed. Far-away objects seem to stand still, relative to the plane. Just wait until you are near a bird …

@Simon could you tell if you were in the passenger seat?

@Dave Yep.  But I'm a petrol head.  It doesn't really matter but the way to car moves off from start and how it scrubs round corners is distinctive.  The handling of front wheel vs rear wheel drive cars is very different.

@Simon, I would like to think of my self as one as well. I will agree the handling is very different but I would be willing to bet your average person in the passenger seat cant tell.

@simon Oddly enough, I used to own a Cutlass Sierra. I adopted it in the summer and the first time I drove it in snow I was amazed to find out it was front-wheel drive. I guess it sort of depends on how you drive. If you don't accelerate very strongly it's harder to tell.

I'm having difficulty seeing the difference between a stationary plane and a moving one.

There is no absolute concept motion. Motion is always relative. Whether something is steady or moving depends purely on your choice of reference. And since this is still the same situation, it follows you can't actually feel motion.
Note that at this very moment, you are rotating with Earth at up to 465 m/s (depending on your latitude; where I am it is still about 300 m/s), orbiting the Sun at 29.8 km/s and orbiting the centre of the galaxy at whoping 220 km/s. Can you feel any of that motions? And how much difference does 240 m/s (reasonable speed for a cruising jet) make compared to that?

When you start the engine in the C172, the blades on the prop are spinning - but the plane doesn't move at all.

The propeller is spinning, and providing some force, but this force is balanced by the wheel friction, and usually the brake friction. Since all forces are in balance, the aircraft is not accelerating and remains steady.

When taxiing out, it feels like the forward motion is being provided by the wheels - like in a car.

Motion is not a thing that could be provided. Force can.
The force to get the plane moving, and to balance the friction so it does not stop, is provided by the propeller. However, the wheels do provide one thing: vibrations.
The ground is never perfectly smooth, so anything rolling on it, be it a car, train or taxiing aircraft, bounces around a bit. Now bouncing is acceleration, and unlike motion, there is an absolute notion of acceleration and it can be felt. And from your experience with cars, you learned to associate the vibration of rolling with motion.

When taking off, you can audibly hear the change with the throttle increases.

The propeller spins faster and accelerates the air to faster speed, so the sound increases.
The increase in power is so that the plane accelerates to the point where it is fast enough relative to air to be able to take off.

In cruise, the plane almost looks the same from the inside as when it's on the ground (i.e. prop spinning). Which is where the weird psychological block is for me - the plane feels stationary even though the horizon/backdrop is moving towards you, and i get that fear kick in that it could drop because there's not enough momentum.

Air does not have the same kind of small bumps ground does. When it's calm, it is much smoother. And while turbulent air may bounce you around a lot, the characteristic is quite different, so you don't get that feeling you associate with motion.
That, combined with the lack of nearby visual references to judge your speed from, means that you don't feel like moving.
You similarly wouldn't feel like moving sitting on the upper deck of large ocean-going ship even though it might be going 50 km/h—the sea surface is too far below for visual reference and the vibration is not there. And similarly you don't feel like moving just sitting at home even though you are still hurling through the space at 190–250 km/s.

As a counterpoint to that large ocean liner, consider the sensation of speed when sailboarding in a brisk wind, with your head a few inches above the water :-)

Answers to points:
1) If you don't have the brakes set, chocks on the wheels, or a rough surface, the plane will move.  Just ask anyone (me, for instance) who's had to hand-prop a plane by themself :-)
2) It may feel like that to you, but your perception is wrong.
3) Yes, the engine & prop noise changes, because you are applying more power, which makes the engine and prop turn faster.  Ever played with a bullroarer as a kid?
4) I'm not sure what you're asking here.  If it's about the appearnce of the prop, that's down to the human flicker fusion rate.  Basically you can't perceive anything that happens more than about 25 times a second - it all just fuses together.  So just as you can watch movies without seeing that there are individual frames, you can't see the prop blades turning, just a blur.
If you're asking why the plane seems almost stationary at altitude, that's because your reference points are far away.  Just as in a car, the distant hills seem almost stationary while the dotted white lines of lane markers blur together.  Or as a practical experiment, find a little-used runway and fly down it a few feet off the ground.  (Also good to learn heading corrections in crosswinds &c.)


text:
What causes pressure disturbances ahead of the wing?
Can someone post a link to a video that shows an example of this either in a wind tunnel or using some other examples?

When an aircraft is flying below the speed of sound, the pressure disturbances will be moving faster than the airplane (think ripples on a pond again), and those disturbances that travel ahead of the aircraft influence or “warn” the approaching airflow. This “pressure warning” can be observed in a smoke wind tunnel as it causes the upwash well ahead of the wing.

Quoted from Flight Theory and Aerodynamics

You may try to search for "upwash", to find things like this.

An approaching body needs to push air out of the way. Directly ahead of it, it will compress the air such that the local pressure increase will push the air out of the way. When the body is a lift-producing wing, the lower pressure on the upper side will suck the air towards it. So what can be observed are two effects:

Air gets compressed ahead of any body approaching at subsonic speed, the more the faster the body moves, and
When lift is created, this pattern will be distorted such that the flow will turn in the direction of the lift-producing suction.

The propagation speed of small pressure changes can be observed with your ears. Sound is just that: Small fluctuations in pressure. An approaching wing is just like an approaching siren, only that the siren emits an oscillating pressure variation and the wing an aperiodic one.
For the video my recommendation is

Note how the flow lines diverge ahead of the airfoil: This is where the flow is slowed down. At higher angles of attack you will also see how the flow lines bend up ahead of the approaching airfoil.

I’d just add that a punch coming at your face also sends airflow with it, even though it does not hit the skin. That’s a practical demo of stagnation flow, carried by the punch :)


text:
Would discharging a firearm in-flight cause an explosive decompression?
I was reading a BBC FAQ about Federal Air Marshals, which has this chilling quote in it:

A gunfight on a passenger airliner is seen as an option only of last resort.

Presuming an air marshal has to discharge his weapon on-board, and it goes through the fuselage, would this be likely to cause an explosive decompression?

yeah I had the same question when I was watching "Non-Stop" yesterday

No, there was actually an episode of Myth Busters about this exact subject:
http://www.youtube.com/watch?v=Fi1_1l7M8FA
They had to try really, really hard to cause an explosive decompression, resorting to actual hollywood style explosives to make it happen.
Most airliners can actually even maintain normal pressurization even with a coffee can sized hole in the fuselage.
As far as firing their weapon on board the aircraft, they are trained to not shoot towards areas like the cockpit or the floor where most of the "important" stuff is.  Avionics, hydraulic lines, electrical wiring, etc. don't take bullets well.  The rounds that they use would put holes in the aircraft, but as the above episode shows it won't create a pressurization problem.

Nice, I hadn't seen that episode of Mythbusters.

In a crowded cabin the likelihood of collateral damage (hitting multiple bystanders per shot) is not trivial.

@DanPichelman Absolutely!  I think that a lot of their training covers this aspect.


text:
What regulations surround fitting aftermarket fuel tanks inside the cabin?
Watching the first episode of Dangerous Flights, a ferry pilot has aftermarket fuel tanks fitted inside the cabin of an old Merlin IIB:

What are the regulatory requirements to be able to do this? / How can you get permission to fit extra tanks inside a plane?
Is there anything that needs to be specially considered when designing the tanks and valves etc?
Is this commonplace when ferry flying long-haul?

This is covered by 14 CFR 91.203:

§91.203   Civil aircraft: Certifications required.
...
(c) No person may operate an aircraft with a fuel tank installed
  within the passenger compartment or a baggage compartment unless the
  installation was accomplished pursuant to part 43 of this chapter, and
  a copy of FAA Form 337 authorizing that installation is on board the
  aircraft.

14 CFR 43 covers MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION.
Basically, it needs to be an approved installation that is signed off and approved by the FAA using a Form 337 - MAJOR REPAIR AND ALTERATION (Airframe, Powerplant, Propeller, or Appliance).  The maintenance shop will take care of that aspect for you.
It is pretty common for delivering aircraft that need to cross the ocean, and there are even companies that specialize in it.  Really, your only option is to purchase an already approved kit because certification costs are so high.
NBAA actually has a nice article which goes into more details, with lots of helpful links.

Since the FAA rules stop at the US border you can install the tanks and just not connect the fittings - then it's plain cargo and 14 CFR 43 doesn't apply. Hook up to the fuel lines at the first non-US stop, tank up, and be on your way. If the install looks professional few intermediate stops are likely to complain about it.


text:
Why doesn't the 737 have a fuel dump nozzle?
I was watching a documentary on aircraft incidents which mentioned that the 737 does not have the facility to dump fuel. Instead they're required to fly in circles to burn off excess fuel in an emergency.
It strikes me as a little odd, as someone without detailed knowledge of the 737-series' fuel systems, that the world's most popular passenger jet doesn't have this capability.
What was the design consideration/reasoning for this?

Possibly part of why it's so popular is that it's cheaper, due in part to not having a fuel-dump system?

TesterMen Tester provided some very good information which I think requires a bit of explanation. The older version of the regulation seems to require fuel dump capability if MTOW is more than 105 percent of MLW. None of the 737 versions have weight limits under this requirement, so based on that regulation, it seems like fuel dump would be required. But as the Boeing info shows, none of the 737 versions have fuel dump capability.
That regulation was amended in 1968 to allow a plane to not have a fuel dump system as long as it can meet certain performance requirements. The current version of the regulation includes this as well.
However, this does not explain why the 737-100/200, which were certified before that amendment, don't have fuel dump capability, when the MTOW listed by the Boeing info above are 108% and 112% of the MLW.
The explanation is that the original versions of the aircraft had lower MTOW, which met the 105% rule. Newer engines allowed the MTOW to be increased, but as rbp mentioned, MLW is based on landing gear and structural limits, so it did not change. The FAA amended the regulation with the required performance option to allow the higher MTOW without requiring fuel dump capability. Also, as explained in answers to this related question, planes can land over MLW, there just may be required inspections.
Note that the similar-sized A320 family does not have fuel dump capability either. Smaller planes usually don't end up with the kind of fuel capacity and takeoff weights that justify a system to dump fuel.

SU-1492 has made an emergency landing several days ago. Landing was successful, but passengers burned in 13000 liters of kerosene. This is the main reason not to fly on planes without fuel dumping system. A320, 737, Embraer, Douglas, superjet, etc -> do not fly on it. Use A340-A380, 747-787.

@puchu there's a whole lot more to that crash than simply having fuel onboard...

@SnakeDoc, It doesn't matter. People were alive after all fails happened. It will be possible to rescue them without/small amount of kerosene onboard. But they were burned completely in hell in about 30 seconds.

@puchu it does matter, things like the airport fire crew not rolling out until after the plane was on fire, and without foam even loaded!... passengers stopping to get their luggage instead of just evacuating, or even the investigation into whether or not the pilot was properly trained to handle DIRECT flight law and possibly have caused the landing gear to fail by bouncing on all 3 wheels multiple times even though there's no reported damages to flight systems. A smaller amount of fuel on board would have still burned and still killed people under the same conditions.

@puchu nevermind the fact that a person cannot choose the aircraft they fly on - no, a person can only choose their destination, the airline chooses the aircraft. Nevermind the fact that the number of aircraft flying daily without a fuel dump system vastly outnumbers those that do, and nevermind the fact that aircraft rarely burn like in this example.

@puchu a fuel dump would not have helped here. Dumping fuel takes time. Time not available when you make an emergency landing. Having a dump fuel system is also a source of failures, when it is inadvertently activated mid flight. Has lead to hull loss before. Your comment is very misleading.

@Antzi, they had at least 20 minutes before emergency landing. 747 dumps 1 tonn of fuel per minute. 13000 liters is 10.5 tonns, so 10 minutes is enough for jumbo jet to purge this amount of fuel. All famous jumbo emergency landings has been done almost without fuel. This is one of the most important reasons to fly on jumbo or derivatives like 777 and 787 or not to fly at all.

@SnakeDoc Popular flights requires large airplanes to handle all passengers so they usually uses modern jumbo or airbus. Use it.

Look, I'm glad you found an exemple where dumping fuel might have helped, but it would be ridiculous to fly only jumbos because of this sole reason: It has not statistical meaningful effect on your survival rate.

Sec. 25.1001 Fuel jettisoning system.
(a) If the maximum takeoff weight is more than 105 percent of the
  maximum landing weight, there must be a fuel jettisoning system able
  to jettison enough fuel to bring the takeoff weight down to the
  maximum landing weight. The average rate of fuel jettisoning must be
  at least 1 percent of the maximum takeoff weight per minute, except
  that the time required to jettison the fuel need not be less than 10
  minutes. This must be shown at maximum takeoff weight, with flaps and
  landing gear up, and in-- {balance deleted for brevity]"
version of 25.1001 effective on 02/01/1965.

It seems that the 737 and also the 757 fit in that Regulation.
2 very nice Regulation Documents

United States Environmental Protection Agency
Boeing Commercial Airplanes from February 2014

I don't have precise figures, but the 737 MTOW is indeed only a bit higher than the MLW. In any case,  overweight landings are not a particularly big deal in most cases - just an extra engineering inspection is required.

i'll just throw the comment in here that MLW is calculated by the strength of the landing gear.

This regulation is very bad. Planes with full tanks should be able to make an emergency landing. Emergency landing includes tanks destruction. But sea of kerosene will explode and kill everyone. See SU-1492 accident.

@puchu: "Includes tanks destruction" is a crash, not a landing.


text:
Which country is responsible for prosecution if a crime is committed over international waters?
Theoretically speaking, let's say we're flying from Portugal to Cuba, on a Chinese-owned airliner. Whilst over the Atlantic, a crime is committed, and we land in the US.
Which country is responsible for prosecution? How is this determined?

AFAIK it's like ships, and the country of registration is the one initiating the proceedings. But in practice most often the country where the flight is diverting to to offload the troublemakers will be the one handling things in practice.

@jwenting I've heard a second option, which is that it's the country where the plane last touched ground, but it may be wrong.

I've heard that too, although I can't remember where I heard it. That said, my first instinct was in line with @jwenting.

Broadly the legal constructs that apply here are essentially the same as for sailing vessels - in other words when you're outside the jurisdiction of any given nation the laws of the country the vessel is registered in apply, and the captain is the one who makes the decisions.
More specifically once you enter the airspace of a nation that nations laws also apply (the same as crossing the boundary from international waters to the territorial waters of a nation - by entering their territory you're obligated to abide by their laws).

If the above doesn't seem murky enough, it's because it actually gets a lot more complicated than that when you start considering all the laws various countries may pass (and subsequently attempt to enforce).
Consider for example The "Special Aircraft Jurisdiction of the United States" in which the US claims jurisdiction over any aircraft in our airspace, or any aircraft in flight which is intending to land on our soil (as long as they actually do land on our soil).
As with most areas of international law going to far down this rabbit hole will likely lead to madness.
For practical purposes you can assume that four bodies of law will govern every flight:

The laws of the country from which the aircraft is departing.
The laws of any country whose airspace the aircraft transits, while in that airspace.
The laws of the country in which the aircraft is landing.
The laws of the country to which the aircraft is registered.

...and if you can avoid breaking any laws in those 4 categories you'll be pretty well covered for most circumstances.

If you really want an International Aviation Law headache we can throw some additional complexity into the mix: Rent a German-registered plane to a US company who contracts a crew out of Canada to fly the thing; now try to figure out whose laws apply while they're flying over the Pacific enroute to Australia.

Prosecution may ultimately depend on a) who knows about the crime, and b) who are they going to tell?

@anthony-arnold I think for purposes of this question we can assume knowledge of the crime is common to all onboard the aircraft, and that they're motivated to see the guilty party prosecuted. If it's an easily-concealed crime, the perpetrator is adhering to the sage advice of "Keep your fool mouth shut!", and nobody is aware it happened it doesn't much matter what law applies :-)

It's an important distinction. Ultimately I think it will depend on who takes you into custody and what they intend to do about it. You won't have to look far to find examples of countries fighting over who has jurisdiction over a crime. Ultimately, whoever has the alleged criminal has the power.

@anthony-arnold Indeed - that's ultimately a problem for the various nations and their lawyers/departments of state & foreign affairs to deal with. My point in the answer is it can be successfully argued that all of these laws apply: A criminal could be charged under any of them, arrested & held/transferred in accordance with any applicable treaties, etc.

I guess you should just try your hardest not to do something illegal on a plane. Although, this can be difficult if, given the situation in your first comment, you have to comply with the laws of half a dozen jurisdictions (and possibly those of the pacific islands whose airspace you cross on the way to Aus).

@anthony-arnold and worse still, in some cases those laws may contradict, making it impossible to adhere to all of them....


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Where can I go to sit in the cockpit of a Boeing?
This might sound like a silly question to some, but is it possible to go and sit in the cockpit of a Boeing 737, somewhere in the UK? (Otherwise in Europe, or beyond).
Maybe at a museum or something? I'm building a [currently tiny] home cockpit based on a 737, and I'd like to see how the real thing looks and feels.
I tried searching online, but I couldn't find anything.
Hope this isn't too dumb of a question, i.e. "not possible Jim!"

You might want to look at this question, which has some links to 737-related data for your cockpit

Any way to mention US?  I'd hate to ask the same question, as it is a good one, I've been trying to find a real simulator for a while

@KORD4me: Flight Experience mentions Coming to Boston this summer but not which year or even which hemisphere. :)

I did read that, still hoping for something closer to Chicago!!

If you're ever in London, http://www.virtual-aerospace.com/product-category/flight-experiences/?gclid=CMas8MvGqL0CFa3LtAod-FgAAQ

@KORD4me See my answer about the Delta museum at ATL.

@KORD4me, not close to Chicago, but the Hiller Aviation Museum in San Carlos, CA has a (older) 737 cockpit to view (open for entry on certain days) and has a 747 nose section (including cockpit) to enter.

Cotswold Airport, near the village of Kemble in Gloucestershire, England.
Cotswolds landing strip, has become the busiest aviation scrapyard in the world.

Usually the cockpit parts are taken out before they end up there, but you never know; you may get lucky and they grant you access for a day. I don't see why not!
Chevron Aircraft Maintenance Ltd is responsible for the dismantling of all Boeing 737 series aircraft.

There is a company called Flight Experience which builds 737 simulators and offers their use to the public. These are fully certified simulators and are frequently used by commercial pilots for currency training.
Their closest location to London appears to be in Paris.
I had an opportunity to fly one of their simulators a few years ago, and it was a lot of fun. We spent some time doing landings at the old Kai Tak airport in Hong Kong.

There are many more such companies.

@JanHudec Can you please name some?

@Farhan: Unfortunately not one relevant for England.

@JanHudec: How about in the US?

@Farhan: Even less:-(.

@JanHudec Found one, but in Canada They have a month long wait time to register.

Flight Safety locations used to have Familiarization classes on some commercial airlines at their locations.  I spent time in DC-9 simulator a few years back while I as attending my recurrent session.

@farhan: Flight Experience has a location in the Boston MA area.  There was talk a year or two ago about them opening a location in Orlando FL, but I don't think anything ever materialized.

I noticed that someone in the comments had asked about the U.S., too. Delta's aviation museum in Atlanta does offer the ability to rent an hour in an old 737-200 simulator. This is a full-motion pilot-training simulator. Their website claims that it's the only one open to the public in the U.S. It costs about $400 USD for an hour.

And it was quite fun, though the graphics are from 2002 at best.

@zymhan Yes the graphics are indeed old. But then so is the plane it simulates. That plane was retired from the fleet 18 years ago. I wouldn't be surprised if the simulator was built in the 1990s.

Bournemouth aviation museum?

BOURNEMOUTH’S popular aviation museum has a new addition – of a more recent vintage.
The distinctive exhibit is an old Palmair jet, a familiar sight at the airport until the carrier closed three years ago.
The Boeing 737-200 carried tens of thousands of holidaymakers from Bournemouth Airport, before being replaced by a more modern plane.
The front half of the white fuselage was unveiled at the museum along Parley Lane last week.

If you're in the South West then take a look at the full motion flight simulator at Jet-Ex Simulation. It's a full 737 cockpit on a moog motion base with 6-dof. They're based in Frome, Somerset.

British Airways' flight training program provides public access to their full motion simulators.
You can book a one hour training session in their 737-400 simulator.
In my opinion, well worth the money, since its a professional and I stress again full motion simulator. In fact, its the same one BA uses to train their own pilots.
They are located in Cranebank.

This is a little bit of an "outside of the box" answer, and I won't be accepting it. I'm just sharing it so there are more ideas of places to do this.
Virgin Experience Days offer 15 minutes of 737 simulator time to newbies for £24.50 in London. I guess I could just tell them I don't want to fly, I just want to "play with the buttons" :P

Your best bet would be SimSpot. This way you can get a real look and feel.
I have been past this spot time after time as is in the Cineworld but never ventured in. It's now on my checklist of things to do 2015 :)

@Farhan thanks for the edit still quite new on here :)

You are welcome. We all are learning here. If you need more help, don't hesitate to join in chat (link down on every page). You'll find many people willing to help.


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Do any airlines hire "pilots" with no previous flying experience?
I've previously looked online for pilots jobs at airlines, from budget airlines to cargo carriers; and they always want you to have a ppl.
Do any airlines currently run programmes for applicants with no prior flying experience?

Please bear in mind that although I've answered this, I'd be very interested to hear of any other airlines with similar programmes.

Which part of the world are you interested in? This strongly depends on region.

@JanHudec Globally

KLM (Netherlands) has their own flight academy, but you still have to pay for your own education (although you only have to start paying off your loan once you're hired somewhere). Not sure if that counts as an answer, since you're strictly speaking not employed - it's just very likely that you will be employed by KLM eventually.

Lufthansa does. They actually prefer people they can train themselves, so they never learned things which Lufthansa considers bad practice.
This becomes impossible if the airline grows quickly. Therefore, all the new carriers (Etihad or Vueling, for example) need to rely on hiring certified pilots.
See Lufthansa-Pilot.DE (only in German but speaking German is a requirement anyway).
Thanks, Danny, for the link. Lufthansa has now adopted English as their corporate language, so I wonder how firm the German language requirement still is.

British Airways ran the Future Pilots Programme in 2013, which offered applicants with only A-Levels (no university degree/diploma) aged 18-55, the chance to co-pilot an A320 or 737.
Financially, this is how it worked:

We have joined forces with Airline Placement Limited (APL), a subsidiary of CTC Aviation, and together we've designed a unique sponsorship scheme that will make flying feasible for all. APL will sponsor your flight training, jet orientation course and type rating.
Obviously this represents a significant investment by APL and you will therefore be required to deposit a security bond of £84,000 with them. Because this is a sponsored scheme, this entire £84,000 security bond will be repaid to you, tax-free, if you successfully complete all training, and join British Airways as a first officer. The security bond is repaid in equal monthly instalments over your first seven years of employment, all in addition to your remuneration package.
There are a number of ways you can raise the funds to deposit this security bond, for example from your own finances, borrowing from family, or securing a loan. If you're not in a position to secure an asset-based loan then you could be eligible for our British Airways guaranteed loan scheme. If this is the case, our partner bank will run a thorough check of your credit history.
Should this come back clear and you pass the Future Pilot Programme selection process, British Airways could act as your loan guarantor. You will then be able to borrow the money from our partner bank in order to deposit the required security bond with APL. On any loan there is obviously a percentage of interest charged by the lender, but the British Airways guaranteed loan scheme specifically offers a 24-month holiday period before any loan repayments commence.
The year 1 basic salary for a Future Pilot Programme first officer is £23,220, with a further £8-£10,000 of flying allowances typically being earned in a full year of flying.

In terms of the licence that you get:

Each training course in the Future Pilot Programme leads to the issuing of a Commercial Pilot's Licence (Aircraft) with Multi-Engine Instrument Rating. Theoretical knowledge (ground school) is examined to Air Transport Pilot Licence standard and so your licence will be issued with 'Frozen ATPL theory credit'. This combination is colloquially known as a 'Frozen ATPL'.

Unfortunately, the programme is currently closed. That said, one source1 says:

All the 2014 slots have been filled and the opening for 2015 slots will probably occur in October or November. You will probably be competing with over 3,000 other applicants for 60 positions, so the odds of success are not high.

1 Ok, the source is Yahoo Answers! That said, the answerer is a top contributor in aviation.

Taking out a loan from your employer so that you can pay for your own training for a job that you'll be locked into for seven years?  Wowsers!  Where do I sign?!  (massive sarcasm)

@SteveV. If I had A-Levels, this would've been appealing to me. The money is repaid to you. Each to their own I guess.

@SteveV. - I see little difference between this avenue and practically any other way you'd get the necessary flight hours for an ATPL. Apply to military flight school and you'll be locked into a certain number of tours of duty if not a full 20-year career. Do it yourself and you might as well take out student loans to pay for all the hours of CPL instruction, that you'll then pay back over 10 years working for hire in small craft, while getting to the 1500 hours for an U.S. ATPL (or by that point forget the ATPL and just fly private jets for the rest of your career, you'll make more money).

Since this has been dredged up from the netherworld... I'm looking at the math of borrowing £84,000, then paying that back from a salary of £23,220. If you manage to max out the "flying allowances" at £10k/year and put every farthing of that into loan repayment, you're in debt for a minimum of 9 years. I don't know what the cost of living is in the UK, but $23k/year doesn't get you much stateside, I can't imagine that it's significantly better over there. Just another example (of the many here at A.SE) that you'd better be serious if you want to be a commercial airline pilot.

@FreeMan If you take the BA loan, you pay nothing back for 2 years. Also you get the money back in instalments once qualified so that would allow you to pay the loan back.

@Notts90 but does the 24-month 'holiday' start when you graduate and are employed or does it include the training period?

Consider the case in Hong Kong.
Both Cathay Pacific and Dragonair offers cadet pilot programmes for people with no prior flying experience. You will be sponsored to attend the flight school at Adelaide and be hired upon graduation.


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Are transponders required for hot-air balloons in the US when operating within a Mode C Veil?
I've taken some people flying recently for fun, and they noticed some hot-air balloons and asked me if they had transponders. In San Diego (Southern California) I often see hot air balloons well within the Mode C Veil (a 30 NM radius circle surrounding from a Class B airport). Do hot-air balloons need transponders when they are within the Mode C Veil?

I wondered if it would even be possible for a balloon to have a transponder. And they do in fact make portable transponders for balloons.

@JScarry I don't think so... 14 CFR 91.215 requires an installed system, and Part 43 outlines what is required for installation, maintenance and testing. That, alongside 14 CFR 91.131, says that the system must be installed to the pitot static system of a specific aircraft (makes sense for altitude encoding), it must be tested every 24 calendar months, and entries must be made in the aircraft maintenance record.  I think the key phrase in 14 CFR 91.215 is engine-driven electrical system.

Keep in mind how a transponder works. Would the balloon even show on radar for the interrogator?  Remember it takes both parts (the radar echo and the interrogator response) for a transponder to have any real meaning.

@coteyr: Couldn't SSR work without PSR echo? I think SSR angular accuracy is better than PSR.

@Canuk "Transponders are mandatory for flights in some types of airspace in many parts of Europe from March 2008 onwards. This includes balloons and other light / recreational aviation and aircraft." Here’s where you can buy them. http://lxavionics.co.uk/lxcart/index.php?route=product/category&path=76_80

@coteyr There are two types of radar, passive and active. Transponders are active. If you watch your transponder, the light comes on when it is being interrogated. It then sends back a signal to the interrogator. If you ever fly at a low altitude out in the middle of nowhere, you might notice that the transponder never lights up. I don’t know for sure, but you are probably correct that a balloon wouldn’t show up on passive radar.

@JScarry A few jobs back we built a transponder package for a hot-air balloon.  The owner was planning some high altitude flights where he needed the capability.  We packaged a GA transponder, altitude encoder, and a battery so the whole thing could be hung in the basket.  The antenna (with a ground plane) hung over the side. It had it's own static system port. It was installed as a minor modification with a logbook entry and then the regulatory checks were performed and logged.  They used a handheld radio to communicate with ATC.  It worked just fine.

@JScarry clarified question: asking about US only.

I've gotten this question enough times to look up the regulations and answer my own question :)
14 CFR 91.215 lays it out quite nicely.  Particularly section B(3):

(3) Notwithstanding paragraph (b)(2) of this section, any aircraft
  which was not originally certificated with an engine-driven electrical
  system or which has not subsequently been certified with such a system
  installed, balloon or glider may conduct operations in the airspace
  within 30 nautical miles of an airport listed in appendix D, section 1
  of this part provided such operations are conducted -
(i) Outside any Class A, Class B, or Class C airspace area; and
(ii) Below the altitude of the ceiling of a Class B or Class C
  airspace area designated for an airport or 10,000 feet MSL, whichever
  is lower; and

Where I see the balloons is definitely outside of the Class B airspace and below 10,000 feet MSL, so the answer is, no, they don't need a transponder.

When do I need to get a transponder?
Within the UK FIR, Mode S Enhanced (EHS) has been mandatory for all aircraft flying IFR as GAT within notified Mode S airspace since 31 Mar 05 (with a 2-year transition period until 31 March 2007), as per AIC 49/2005 (YLO 171).
The carriage of a Mode S Elementary (ELS) transponder within remaining UK airspace has been mandated by 31 Mar 2008. It is likely that there will be a 2-year transition period until 31 March 2010, to allow for any implementation difficulties.
Within other European Mode S implementing states, the target for Mode S (EHS and ELS) implementation is 31 March 2008, with no exemption period!

What is Eurocae ED115?
ED115 is the agreed technical standard for LAST Mode S transponders.

Quoting something that refers to the year 2010 as being in the future, with no further explanation, is not super useful. Especially when it doesn't seem to be applicable in the first place.

IFR??? In a balloon? WTF

@VladimirF - I suppose maybe. I mean you could use instruments to see height and wind direction. I suppose you could use them to see how far off course you are. You could tune to a VOR and use a CDI to see how screwed you are. I guess it would work.  I"m not really sure how you would make a 1 min turn, or adjust headings, or why you would be in a balloon when you can't see anything but https://en.wikipedia.org/wiki/Breitling_Orbiter So maybe?

@coteyr I doubt that would work. Do you have any indication Breitling Orbiter was an IFR GAT flight?

no not at all, I'm just stating there are many kinds of hot air balloons and the really high altitude ones, or the ones that are designed for "rough" weather have to have some kind of "instruments".

authors: Vladimir F Героям слава